Fountain pen



May 3, 1960 F. R. WITTNEBERT ETAL 2,935,044

FOUNTAIN PEN 4 Sheets-Sheet 1 Original Filed Oct. 24, 1955 @WMV/4.23m mrT www.

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May 3, 1960 F. R. WITTNEBERT ETAL 2,935,044

FOUNTAIN PEN Original Filed Oct. 24, 1955 4 Sheets-Sheet 2 IN V EN TORS.

F. R. wlTTNEBr-:R-r ErAL 2,935,044

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'meng and 'constant and yuniforrnjilow ofY ihk'p'i l A2,935,042: FOUNTAIN L:rEN

Frederick R. witmeberf, whitewater Township, walworth County, Raymond L. Spaulding'Janesville, and

Ray A. Lawton`lVlilton, Wis., I'as signors to `The Parker Y Pen Company, Janesville, Wis., a corporatio'nofviWiscousin l This application is avicontinua'tionfbf applcationfSerial No. 542,224, tiled October 24,4955, nowfabandoned.

`.The present invention relatesgtofafountain pen.

`The invention is directed r,to a fountain pen'of basically new concept including desirable `features 'of a, capillary -pen and a vacuum-reservoir; pen.

A broad object of ktheinvention is toaprovideia fountain ,-penfhaving Ithe characteristics-with respect to filling o`;a capillarypem andv with respect to `feed controlsthedesir- Aable characteristics offa vacuum-reservoir pen.

A `capillary pen as heretoforezknownisapen that lls solely by `capillary;action,;retains the inkin .the pen, by #capillary action until it, is written out'through Vthe writing Velement vor `nib-whichgis1alsolyby capillary act-ion. The

ink is retained or held by capillary means which. includes a main reservoir portiony and afeed portion of substantially lesser capacity than the reservoir portion leading Y from` the latter vto "the nib. v"Ilieffeed :meansfalsolserves asia reservoir means, tothe extent of itsfcapa'city, :but The capillary-Y-irieans 'constitutes the 'sole meansfor lling the `pen and storing ink'there'in. vIt lls merely upon inserting 'anv end of lthe capillary means, eitherthereservoir portion-or feedportion, in va body of ink. The ink is held ftherein'no'r-rrially in a stable or 'balanced condition by balancedfforcesn acting thereon, including-the capillary'attracti'on fof-the capillary means,.-vand gravity. When lthewrit-ingelement -is applied tol 1an surfacev fasfinwriting, ia` greater-capillary force ises'tablishe'd, 'ment and surface which vdestroys the balanced condides'ignetdlg 'between 'the writing eletion mentioned, and because of the lgreater-capillarityI so established, the ink is drawnout of the capillary means onto lthe writing surface. Such feed ,or drawing out of v l 'fa vacuum- The` :weight jof "the ink, or fhead jp'ressure (iie., gravity, as riote'd' above) is a factor 4inthe control 'of the ink; when thefreservoir means iS'fulLLfor example, 'the headof ink exertsja relatively 'great'force land jte'nds ,to cause the ink to pass or'ovv more freely out onto the `Writing surface, `but as lthe ink is writtenoutand the Yhead 'lowers, the lesserI head 'does not `haveth'esarnejiforce in causing theinktodiow out, and as arresult there is a tendency for thecapillarity ofthe capillary means to exert a relatively greater ,force and hold Lthe' ink"back A'from Vbeing written butfr'eelyfand uniformly Jtliroughthe writing'element. The result would belfor `the line Aformed .`to..be vprogressively' fainter,` and the "ow `of ink, n btjto terminate abruptly. "This condition has befenwgreatly V'over- 'come by` providingA graded c'apillarity in the. capillary means, decreasing in 'direction toward the "writing el@ ment, so that, as'theink is .progressively 'writtenrout and 'the head lessens,the kreducedhead :is compensated by the lesser capillarity progressively Lnearer the `writ1 n eleuntil it is completely written out. l,Hovvevevrfvtlie [fgraded capillarity, although attainablertoaalhiigh degree "bf perfection, 'requires great 'precision manufacture,

,'tion. ,'Thejsame ,capillary action that `fills the pen tends ly after `'filling and when the pen is reinverted topoint- A 2,935,044 Patented May ,3, 1.9.60

land-'it is rdesired that tltlenecessity for such precision lbe overcome, and it is overcome by this invention.

An lobject therefore of the invention is toprovide a vcapilla*ry-filling 'fountainpen inwhich more perfect flow of, ink in thegwriting-out,operation is attained, and more jparticulaily that the ink ows freely andruniformly Iuntil the reservoir means isessentially emptied.

,Y .Another'featurefof the invention has todo with 'the "fe'ature wherebythe pen liills by capillaryA action and the feedoutvisunder 'controlof Va vacuum-reservoir condi- "to' retain they inkfin the4 penafter illing,and in order that ,thejvacuurn-reservoir, condition ybe eiective` for lthe purtiose, @intended the` capillary action must 4be insuliicientto r-holdthe ink inthe Vpen in writing notwithstanding ythe fact that it is effective, for ,lifting the ink into it in iilling. yThis,arrangement'can be brought about by changing the .attitudeof Vthe pen with respect to the filling position and fthe writing position, i.e,.,vin the filling position the capillary reservoirv element is `so .disposed that it is capable of substantially filling by capillary action butin writing Vposition it isso .disposed that it is incapable of retaining irik therein. 1 It is therefore a further andmore specific object to provide apen of the general character vnotedhaving a capillary reservoir. element and capillary feed means betweenthe reservoir element and writing nib in -which by inserting. therear end of the reservoir elementin a rbodyof inkitsubstantially iills, and when it is in writing position with its point end down the reservoir lelement is..posit ioned. abovethe feed means so that the reservoir element Y. and y'feed means Aform "a continuous capillary means and the capillary holding power of the reservoir Jelement .isinsuflicient to retain the :ink at. the height of ,theY reservoir elementand feed means combined.

Another object is to provide acapillary-iilling pen .having a novel constructionincluding an overow collector for receiving'ink in excess of that required for writing.

Afurther object is to ,provide a fountain pen having an overllowlcollector-of substantial capacity for receivling-ink in excess of that required vfor writing purposes,

`.-notedin .whichbecause of the drain-back, possibility of leakage of the pen is greatly reduced.V Y

Stillanother object is `to provide a'fountain `pen vthat lls by capillary action and has removable `means for ,closing the reservoir for enabling a vaccum condition to be produced therein, in which novel valve-means is provided which enablesinkto pass therethrough in the filling operation but forms at least na` temporary closure vfor producing a vaccum conditionin the reservoir immediateend-down position, and until the removable closure means is applied, to the pen. n

lfmothe'robject is to provide a rcapillary-filling fountain pen thatA is highly resistant to leakage due to jarring.

vfurther feat'urero'f 'the invention has to do with a phenomenon of capillary means with respect to its capillary holding power. vLlhe capillary-reservoir element of an ordinarycapillarypen is constantly exposed to air (to rwhatever extent it is not filled) and is under attack by `the.i'rnpurities in the air' which eventually may impair its capillary qualities, with consequent relaxation of the 'holding `power thereof.

VSuch-a condition is not necessarilyl related to defect in the device, but the result of ,deterioration `from age as 1n .the case of lly'device. In

vSuch event and when the penis jarred, tbeliabilityuto leakage is increased.

Another object therefore is to provide a pen in which the advantages of capillary filling are attained while a closed reservoir and vacuum-pressure condition is utilized in holding the ink in the reservoir whereby to insure against leakage of ink through loss of capillary holding power.

A still further object is to provide a fountain pen having a capillary reservoir element that fills by capillary action, and novel feed and control means including a capillary passage with an ink control weir therein and an extension of the passage into the capillary reservoir element arranged so that the weir senses the head of the ink in the extension of the passage, the arrangement being such that the ink in the passage assumes substantially the same head as in the reservoir element with the advantage that the reservoir element with its vast number of inl; storage spaces, as it must have, need not be constructed with precision in order to produce good liow control since the accuracy required may be provided in the feed passage which can be done with facility.

Another object is to provide a fountain pen having a capillary reservoir element and feed means interconnecting the reservoir element and a writing nib, in which a novel arrangement is provided for eiciently feeding ink from the reservoir element to the feed means.

A further object is to provide a pen utilizing vacuumresewoir condition for controlling flow of ink to the nib, in which irregular line intensity through a breathing cycle, as has heretofore occurred, is substantially reduced.

Another object is to provide novel means for capillary transfer of ink to the writing nib including a capillary resilient pad associated with or on the nib, eliminating necessity for precision in manufacturing certain parts of the pen.

A further object is to provide a novel mechanical construction of pen capable of carrying out the broader objects set out above. y

Other objects and advantages of the invention will appear from the following detail description taken in conjunction with the accompanying drawings in which:

Fig. '1 is a side elevational view of a pen embodying `Our invention;

' Fig. 2 is a view of the pen with the barrel shown in section and the internal elements in elevation;

Fig. 3 is a longitudinal sectional view of the pen, on an enlarged scale relative to Figs. 1 and 2;

Fig. 4 is a sectional view of a portion of the barrel as viewed on line 4-4 of Fig. 3; l

- Fig. 5 is a cross-sectional view, on an enlarged scale, taken on line 5 5 of Fig. 3;

Fig. 6 is a cross-sectional view, on an enlarged scale, taken on line 6-6 of Fig. 3;

Fig. 7 is an elevational view of the rear end of the reservoir casing;

Fig. 7a is an elevational view of the rear -end of the ller valve plug;

Fig. 8 is a cross-sectional view, on an enlarged scale, taken on line 8-8 of Fig. 3;

Fig. 9 is a longitudinal vertical collector;

Fig. 10 is a plan view of the collector;

Fig. 11 is an end viewof the collector as viewed from the right of Figs. 9 and 10;

Fig. 12 is a sectional view Fig. 9;

Fig. 13 is a plan view of the feed bar;

Fig. 14 is a longitudinal vertical sectional view of the feed bar;

Fig. l5 is a cross-sectionalv view taken on line 15-15 of Fig. 14;

Fig. 16 is a cross-sectional view taken on line 16-16 0f Fig. 14;

Fig. 17 s a cross-sectional view taken on line 17417 of Fig. 14; Y

taken on line 12-12 of lsectional view of the parts a decorative effect.

Fig. 18 is' a cross-sectional view taken on line 18-18 of Fig. 14;

Fig. 19 is a view illustrating the manner in which the pen is filled;

Fig. 20 is a large scale sectional view of a portion of the rear end of the reservoir casing showing the details of the structure of the casing and its relation to the filling operation;

Fig. 21 is a semi-diagrammatic view representing a certain step in the filling operation of the pen;

Fig. 22 is -a view similar to Fig. 21 showing another step;

Fig. 23 is ya semi-diagrammatic view representing a step in filling a modified form of reservoir element;

Fig. 24 is a semi-diagrammatic view representing a phase of capillary action in holding ink in the pen; and

Fig. 25 is a fragmentary view of the writing-tip portion of a pen showing a modifiedform of nib. The pen embodying the principles of our invention is shown as a whole in Figs. 1, 2 and 3. The pen is shown without a cap, since it may be supplied with an ordinary cap forV carrying in the pocket, or alternatively the pen may be designed for use as a desk set pen in which case the pen is inserted in a receptacle on the base of the set. In the present instance, the pen represented is of suitable proportions for use with a cap for carrying in the pocket. It may assume any external shape insofar -as its relation tothe internal elements are concerned, but from the standpoint of appearance it preferably assumes a long tapered or curved shape as best shown in Fig. l. For convenience the writing-tip end may be referred to as the front or lower end, and the opposite end as the rear or upper end. i

GENERAL Reference is first made to the main parts of the pen and their general location relative'to each other, cach of which will be described in detail later. The pen includes a barrel 14, a capillary reservoir element 16, a casing 1 8 for the reservoir element, a feed bar 20 leading from the reservoir element to a nib 22 at the forward end of the barrel, and a collector 24 interposed generally between the reservoir element and the nib.

The various elements of structure making up the pen may be of any desired materials except as hereinafter specifically pointed out. Generally speaking, the materials unless so specifically referred to may be made of the usual plastics and metals heretofore in use in manufacturing fountain pens.

Barrel The barrel 14 is made of two sections detachably secured together, one of the sections being readily removable from the other by the user for filling purposes. The two sections include a front section 26 and a rear section 28 secured together by suitable means such as a connector sleeve 30 externally threaded for engagement with cooperating internal threads on the respective barrel sections. The front section is sometimes popularly referred Ato `as a shell and the rear section simply'as the barrel. Preferably the front section 26 is semi-permanently secured to the connector sleeve by means of suitable cement of such character that the user may not readily detach the section from the sleeve but that a repairman may detach it under proper circumstances.` The sleeve 30 extends into the front section and forms a shoulder 32 for cooperation with certain other elements in the assembled pen. A barrel band 36 of generally L shape cross-section surrounds the connector sleeve, with an axial portion engaging the sleeve and a radial portion engaged between the meeting and edge surfaces of the barrel sections. This barrel band, and particularly the radial portion there` of, serves as an abutment for engagement by the barrel sections, and also to form a ring on the pen which irn- The barrel band may be seuredin'place by suitable means such as bya cement or tij', anfassen. j

'e '-a'xfal portion section, has a counter-bore @3'8"t'ore'ee1v' -ffth barrel band.

The N rei "fein intensif-ehesten which includes fseetizori "42 in'tlie reafportion, `the` feed and rservoir sectionsfrlotilecssrily eoriespo'nding exactly'to the barrel Ls'tikiis '26"ar 1d Z8. Thefrb't barrel section 26 is provided 'with laireducedfdiniehsion. bore 44 opening through "itsffrontndfnd 'h"l tapered hood portion 46 overl ion of "the 'nib and providing at a' fcylndri'cal surface 48 cooper- `lalltltferservingas.a'deporativepiece. l.

The Irear barrel section '28 includes therein a sealing :v'yalv'e assembly i60g operative for closingy and sealing the 'reare'r'id ffthe re'servoix"Y casingIS when thewbarrel sec-- l'ricludefs 'a 'valve guide 62, whichjma'y suitably be tapered 'tf'coriforn "with the taper ofthe 'inner surface of the `barrel ,section land 'fitted fin Yplace in' any 4suitable manner ils'uchfs 'by a"cenient. Thevalve 'guide 62 has a bore Y64 receiviii'gfa'f'stemfte f'falvalve plunger 69 the rear fslot'td Vvand'sjlttaped to have` an' venlarge- A"the bore. The frwdend fof the1ste`r'n is provided with "a forwardly opening cup 70, and a compression spring v'12 "surrounds" the stem `betv'veen -the ,element 62 and cup 'forwbi'asingthe .plungerf69 lnf'orwar'd direction, Secured withinithe "cup 70 is faresilient valveseat 74 which itself is .cuplshaped forfegagingtlie .rear end etremity `of the casingmlS and closing the llatter when'the barrel section is in place. The element 74 may be of desired material, such as a plasticfhaving suitable resilient and sealing characteristics, and-whichof course isfnottdeleteriously affectedjv-,by the-inl:I used-in the` pen. jThis element maybejsecured inf-the cup 70 by any suitable :means suchfas yby alce'ment The reservoir-element 1'6-is ofcapillarynature, i".et, it

" llsby capillary action lin-jrespnsertoanlend' of the element being inserted va body of ink. The element A*is more exactly referred to as a fll'erand-'reservoir ele- 'fment because ofits comprehensive nature in -beingfcaip'able yof filling and'holding inkby-capillry action. For 'convenienceherein,"however, it will be referrdto simply tionf40 rin the front endfp'oitinf and al reservoir 7 rriayfbe utilized. The' valve 19-:ofwhi'ch thespecic pur- =:asfareservoireieinent. The element constitutes substan- -tiallythe 'fwho'le reservoir "means for holding 'in'k in Ythe pen l The"res `e'r'vir element includes' one or frnorelsheets of thin materialrolled'iin spiral fashion to 'forrn a'plurality ofi radially spaced :wall elements. These wallelenients form between adjacent ones thereof ink storage spaces 4of capillary dimension-teg., -.008 in -wall-toV-wall diinension, see below), which,` due to the spiral-wrap construction, extend longitudinally ofthe element. Figs. 3

'and 6 show to `best advantage tlle'detaily constructiony of the reservoir element V16. Iheradially spaced wall elel the filling apertures.

v`s`e1ted`ir1 Figs. 19 and 20. low, aslin Fig. l20,there may be 'a tendency for any sedij'inent"thathappens to be in the 'bottle to pass into the *Pen b'ut'thedome element 82 preventsthis occurrence by y spacing the' vapertures 84 and ller valve V19 vfrom the extrerne` bottom of the bottle. 'l adjacent the 'transverse vplane .including the outer surj zface of the filler valve, and any tendencyof...airito be 65 tlie'sp'ce's78. The capillary'spaces' 78 a'r'efactuallyportions of a continuous space since the convolutions or wall elements form a spiral space, but for practical purposes `they "may beconsidered discretespaces Idisposed-relatively radially. 1A suitable `reservoir element Vofthe Tabove vgenjeral nature `is disclosed Tand claimed in Bartell `Patent 'No. 2,522,555; dated September 1'7, -1 950.

The spiral vreservoir element surrounds itheifeedfbar 20, the llatter extending rearwardly oriupwardly throughout the length of the-reservoir-element'aswillbe brought out in detail later Vin connection withthe Vmanner.of'f'ieed ofink from the reservoir `element tofthe nib. Y ,v

The reservoir element.16.isiencased in'thecasingfil-'S which for the greatergportion ofA its length Ais cylindrical in shape, 'and which atits .front-:end :isfsecured ftothe 'collector 24. `A -llerivalve `19--is positioned iiuz-the-jrear rend of the casing and covered 'by the end :element ,iof the casinig'whi'ch includes a centraldornegiportion x82 around theperiphe'ry 'of which are Va plurality -of flling apertures 84, therebeing Aalso;an internal fsbould'er'i-S surrounding the dome-portion. The endelemen'tisxcompressed or formed to fn-shape. .The'f'shoulder forms a stopelement foreng'agement by the liller valve 191whch also engages thedome portion and isiexposedthrough The ller `valve 'is in theforin of a slug, Vofgenerally "cupishapeiform, and is vmade Vof-fhighcapillarity material-of greater capillarity `than:tliek reservoir element-preferably.felt, but other-material 4'having the desired characteristics fsuch "as 'sponge, 'mesh, etc.

pose 'will-'be'1e'xp1ained fpresently, may be "spaced from,

Aor engage,`the reservoirelerne'nt 16. In .theipreseiit invstance the .valve isspaced'frorn the reservoir element,

' ment. The ribs receivetherear end of thefeedfbar with Ta loose't and prevent yexcessive'-"s'ide,play ofthe feed bar. :A "spatie or 'void'is thu'sformed between the -llervalve 119 arid reservoir element 16,this space inelidi'ng the f'space91 and a'pert'ures "90. `Itis` within 'the icion'pass (if vthe invention, ihowever, to have the reservoir element egafge'tlie j'filler valve.

The domeeiemem s2 andthe spense-arrangement 'ef 5'0' fthe;i'illingefaperturs iin' addition to :providing protection for Athe iiller 'valve Y 19, serves "tof -'prevent sediment finfthe "'bett'hr of jbottlje f i'nl -rfrom v-Abeing vdrawn info the -`reservoirelenentwhile at the'same timeeliniinatingny "tendency to'trap air. Filling of thepen-is accomplished by fremovingthe rear barrel section and inserting `the reary endof ythe 'casing 18 into a lbody of 4Vink as repre- If the leve'l of the inkfis The apertures are closely trapped inthepen due to the upward movement of ink from the bottle into the pen is eliminated since the'air will readily flow out through the illingapertures,` particularly since the felt `forming the valve 19 is curved,

f having Vits convex surface exposed outwardlyor ,rearwardly and disposed in yor closely adjacent the lling apertures 84. Y

The frontend of vthe reservoir element 16 engages'the rear end ofthe collector 24. lFeed ofi'nk is accomplished 'mainly V'tlftr'cnigh ,passages in the vfeed bar4 -2'0` but 'alsojaiid "7 through spaces formed by the feed bar and collector together, as Well as spaces formed by feed bar and nib.

Feed bar The feed bar 20 may be of such material as plastic, and extends from a point closely adjacent to the writing tip of the nib to the rear end of the reservoir element 16. The material of the feed bar has sufficient rigidity that passages of determinate dimensions can be formed therein to 'compensate for lack of this property in the reservoir element, as explained fully hereinafter. The feed bar is generally cylindrical from its rear end to a position adjacent the frontend where a cut-away portion forms a flat 94 forwardly of which is a second flat 96.

The feed bar extends throughthe reservoir element, as pointed out above, and through the collector 24 from which it extends into and nearlythrough the nib as well as the'reduced bore 44. -The forwardmosttip of-the feed bar closely approaches or engages the under surface ofthe nib in an arrangement working toward accurate spacing between the feed b'ar and nib.

Capillary forces play a great part in the feed of ink from the reservoir to the nib, as well as in the reservoir element itself as in this case. The term capillary as used herein is intended to denote a `space or passage of sufficient capillarity to lift ink a substantial distance. Such meaning of the term as vused in fountain pens will be understood by those skilled in the art.

The feed bar has a plurality of passages or channels of capillary dimension extending substantially throughout its length. These passages or channels are 'in the form ofgrooves or slots and are represented most clearly in Figs. 13 to 18, inclusive. The passages include two primary feed passages 98 flanking a centralvcontrol passage 100. The feed passages 98 are uniform in cross section, and uninterrupted, throughout their length which is substantially the length of the feed bar. Each of the feed passages 98 includes an outer wide portion 102 and an inner narrower portion 104, both of which are of capillary dimension. As an example of suitable dimensions that may be utilized, the outer portion may be .005," and the lower portion .002, in wall-to-walldimension. The outer larger portion determines substantially the capacity of the passage for conveying ink, from a practical standpoint, while the inner and smaller portion serves as a pilot passage for facilitating feeding ink from the'reservoir element toward the nib after the ink has been drained back from the outer larger portion, as will be explained in detail later.

The purpose of the control passage 100 is to control reservoir vacuum pressure and hence control the ink flow, but the passage is arranged so `that any ink that should flow downwardly therefrom, which would be only in extraordinary circumstances, would nd its way to the nib. The control passage 100 includes a segment 106 beginning at the rear ends of the feed channels 98 and leading to a second segment 108, which will be referred to as a Weir, which in the assembled pen is located below the reservoir element. The weir is of lesser effective dimension and greater capillary than the upper segment 106 and serves as the portion of all ofthe passages through which any air passes from the exterior into the reservoir when any such air is needed to replace ink withdrawn'f'rom the reservoir. Hence the Weir serves as the sensing and control means for controlling the flow of ink from the reservoir to the nib. The direct action of the weir is to hold ink therein by reason of its capillary dimensions. It acts indirectly to control passage of air into the reservoir means, and thus may be referred to also as a Weir-vent. The location of the Weir is not necessarily as illustrated, but may be higher or lower than that location. The illustrated location is as desired however, in consideration of such factors as the o length of the column of ink to be controlled and desired `the at surface 94 of the feed bar.

relative dimensions of the Weir and other portions of the ink feed passages and reservoirispaces.

Leading forwardly from the Weir 108 is a third segment which may be'larger than capillary dimension for receiving any ink that should ow from the Weir. This segment opens laterally into and communicates with the feed channels 98 (Figs. 13 and 16) and terminates forwardly a substantial distance rearwardly of the front end of the feed bar. Hence the central control passage 100 does not communicate directly with the nib but it communicates therewith indirectly through the side feed passages 98. The segment 106 of the control passage, similarly to the feed passages 98, is provided with an inner pilot portion, such as 112, the purpose of which is to .provide counter-flow of ink inforward direction as air considered great relative to the width and not affecting the capillarity as determined by the. width. The feed passages 98 and control passage 100 exten rearwardly substantially to the rear end of the reservoir element so that the ink storage spaces in the reservoir element have direct communication with the ink passages at all points along the length thereof. Fig. 6 represents the relation between the ink storage Spaces 78 and the passages 98 and 100, where it will be seen that the open sides of the passages communicate directly with the innermost ink storage space 78. This communication extends longitudinally the length of the reservoir element and ink easily linds its way from that innermost space 78 into the passages. Ink also easily passes through the v.apertures in the wall elements, from the outer spaces 78 `reservoir element to the central portion is readily accomplished. Air ow as well as ink flow takes place through the apertures in the reservoir element, so that, as the ink flows out, air readily replaces it. As will be pointed out later, ink also passes longitudinally in the spaces and through the front end of the reservoir element.

p Nib y The nib 22 includes a writing point 114 and a rear body portion 116. The rearmost part of the body portion is generally tubular as at 118 (Fig. 8), but split on its under side at 120 for providing the desired resiliency for engaging with the collector 24 in which it is mounted. This portion is self-biased outwardly for frictionally engaging the inner surface of the collector. Forwardly of the tubular portion is a pair of wings 122 (Figs. 5 and 8) bent inwardly in a transverse plane and engaging This engagement serves as an interlock between the nib and feed bar to prevent undesired rotation and displacement of the nib. The nib forwardly of the wings tapers to the writing point 114 which is provided with a slit 124 leading from the writing point rearwardly. A pierce 126 may also be provided in a suitable location, e.g., at the rear end of the slit. The nib has firm mounting in the collector, and by that mounting its forward portion is normally held out of engagement with the surface 48 and it thereby forms a space 128 therewith. In such position of the nib,the wings 122 rest on the shelf-129 in the lower surface of the bore 44. The nib thus has support at its rear end in the collector and it further receives firm mounting through engagement between the wings 122 and the undersurface of the feed bar, and the shelfv 129 under the wings. The wings exert an upward inuence on t out above.

t Collector The collector 24 hascertain capillary passages formed therein, and forms with the `feedbar andfnib certain passages, together forming communication between the reservoir and the'nib. The' collector alsoisr provided vwith a plurality of capillary overow -cells, for receiving ,.ink in excess of that requiredl for -writingpurposes "As amechanical matter, the collector `serves to aid in solidly .mounting other elements of the pen, being of substantial sizek and directly engagingfthef-front barrel section-26 or other solid portions of the pen. v

VThe collector is generally of Vtubular form having a diameter than the first. The feed bar extendsfthrough .the collector, receiving'mounting in fthe-1 main bore porn tion 132 and forming certain passa'ges'withY the`surfaces o ofA other rborerportions. The front end of the collector vhas, a reduced portion 140, forminga shoulder 142, -which Vis fitted in a similarly-dimensioned bore portion t v14.4 in the front barrel section.y The elements are relatively 'dimensioned to'provide-a'rsliding and snug fit to enable the collector to'beeasily inserted andvremoved, but preventing undue play thereof in the assembled pen. .The shoulder 142 engages a corresponding shoulder 146 ,in the barrel section for limiting forward movement of the collector, and on the underside of thereduced portion 140 is a notch 148 receiving a correspondinglug 15o inthe front section to interlock the collector with the barrel section against relative' rotation therebetween. 'The rear end of thecollector includes a portion 152 telescoped into the front end of the`casing 18 and'secured thereto, this securernent being by any Asuitable means such `as a heat stake arrangement of :known kind. In `this arrangement, the rear end of the collector lis engaged by the front end ofthe reservoir element asv was pointed mounted in 4the barrel. The internal elements, it' will be observed, constitute `a self-contained unit, these elements vincluding the collector, feed bar, nib, reservoir element, and casing which can be removedas such unit from the front section, upon removal of the `connectorsleeve 30 as by va repairman. So longas the yconnector"sleeve, 30

:remains in the front barrel section, tit serves'as the means for retaining the unit therein. Vthe shoulder 32 acting through 'a resilient sealing ring 156 which in turn engages a shoulder 158 on the collector This Yis 'done 'through forwardly of the rear portion 152. This sealing 'ring yengages those two shoulders, the forward endof the Nare thus sealed against leakage'from the front barrel section. .When the rear barrel section isreroved, the frontisection and casing 18 form any enclosingenvelope for the reservoir element, feed means and nib.

The feed bar snugly fits the surface of the bore'portion 4132 of the collector, and is preferably heat staked thereto, vin a known manner. `The cylindrical portion of the feed bar extends forwardly beyond the bore portion 132 so that it forms an annular passage'160 between itself and the surface of the counterbore 136. This passage is of capillary dimension and is annular in form from its rear end to the flat 94, and from that point forwardly it is at least arcuate in cross section whereV it is continued in similar vdimension by a lpassage 162,'

between the feed bar and the nib. As will 'be observed ,esente 'approximates the thickness ofthe material 'formingfthe .nib wherebythe dimension of `the` capillaryspace 162 'approximates thatof the capillary space 160. The spaces `160 and 162 'are continuous, 'the'rear end' of the nib continues from the rearend Aof the nib forwardly toa with that of the collector 2e, which in turncoincides with that'of the pen. VThe'parts'a're Vso `relatively shaped "and located' that there is a `tendency to interference between the" wings 122 of the nib and the feed bar. The feed bar is" slightly flexible and susceptible to having its front' portion lifted or bent slightly upwardly. The wings thus Aexert such upward'influence,"as mentioned above,

"while 'thewings'receive support from 'the shelf 129. The

effect of the 'collector-feed bar-nib relationis to retain the front end portion of thenib downwardly to `form the"sp'a'c`e"128 and to retain `the top'surface of the feed bar in engagement with or`clo`sely adjacent the under Hsurface ofthe nib.

Thecapilla'ry overflow cells in the collector for receivin g :theexcess ink are formed between a'plurality of 'radial fins l'surroundingl the bore "of the collector. These cells 166 communicate through 'certainlbassages with theTeservoir elementfand with the`nib. The prini ciple of 4operation 'of the 'overflow ycollector` is fully The casing 18 has snug engagement with:A 'the connector-sleeve 38 whereby the collector has solid fengagement at'its ends with the barrel or elements solidly i drain-back passage.

casing 18, and the inner surface 'of the barrel'section Aat Y Vthat location. All of the elements in the unit mentionedY 60.

described in Baker Patent No. 2,223,541 dated December 3, 1940,' but'referencetocertain phases thereof is made herein for'convenience. Briefly, it may be stated that the cells of the collector Vvreceive or draw in excess ink when an overnw condition exists and later release it to the nib in writing.y Later reference thereto Ais made hereinbelow. -Thevcellsr extend circumferentially'of the collector except as interrupted by aV capillary passage 1,68 in the lower side and a passage 1 70 in the upper side which-serves as an air channel. The passage is substantially greater in dimension (.040) than the passage 168, and herein regarded as of greater `than capillary dimension. The collectorand front barrel sec- "between the fins 164 and surface `of"`the barrel section.

,This space lis of capillary ldimension Iand will'u'nder the most adverse conditions serve Has an overflow. space.

The passage 168 may be referred to as an overow and It is approximatelv .005 in wallto-wall dimension and is cut entirely through the finis, communicating with all the cells, and through the body of the collector into the central `.bore where it communicates with the passage 160. Thepassage 16S continues rearwardly through the length of the collector and opens through the rear end thereof. vA linking portion 172 bridges the passage inthe rear portion f the collector to provide a circumferentially continuous rearY end portion. This link is of minor radial dimension, of sufficient size to provide the necessary strength but small enough to provide great radial dimension, -and corresponding capacity, of the passage 168 at that location. The passage 168 rearwardly'of the link v172 communicates with the diverging bore portion 134 in the rearrnost extremity 174 of the collector. This portion of the V'dimension of. the spider and opening rearwardly there- :through where these slots as well as the passage 168 `communicate directly with the ink storage spaces in the .reservoir element. The diverging surface of the bore portion 134 forms with the feed bar a rearwardly diverging space 178 which at its rear end and greatest dimension is of capillary dimension and of course its capillarity lincreases in forward direction. As an example, the radial `dimension of this space at its rear end is approximate- :ry .006".

The radial slots and passages 176, 168-receive ink from the forward end of the capillary reservoir element :and convey it radially inwardly into the space 178, and Abecause of the immense capillarity of that space at its for- `ward end, the ink quickly fills it in circumferential direc- ;tion. Thisink progresses rearwardly to completely fill :the space and then readily passes into the capillary passages 98, 100 in the feed bar. -In this manner, there- Yfore, the passages in the feed bar receive ink from the nular recess and the counterbore 136; passage 184 .formed in the counterbore by the fiat 94 on the feed bar; passage 186 leading forwardly from passage 184 and formed'hetween the flat 94 and lower tubular portion of the nib; passage 188 below the wings 122; passage 190 cut through the shelf portions 129; and finally passage 192 between the fiat 96 of the feed bar and the lower surface of the bore 44.

. Aperture 196 communicates between the passage 170 and the bore of the collector and in that way provides free flow of `air into the collector and into the control passage 100 in the feed bar through which it passes into the reservoir space when there is needrfor Vair invthat space to replace ink withdrawn therefrom.

Operation Since the pen fills by capillary action, the pen should be open for filling, i.e., arranged so that a free air passage is provided whereby ink in entering by capillary action through one passage forces the air out throughanother passage. Such arrangement is provided inv the present case, the pen fills through the rear end, and air is forced out through the front end. To fill the pen, the rear barrel section is removed fromv the front section and the rear end of the casing is inserted in a body of ink as represented at 197 in Fig. 19, to a depth that the ink level is above the rear (then lower) end of the reservoir element 16. The hydrostatic head of the body of the ink -forces ink through the filler valve 19, fills the space bevtween the valve and the reservoir element (when such -space exists), and then enters the reservoir element. The Vdesign and .relation between the parts are such thatthe written out on a 'writing surface, tension is imposed on the column of ink and air enters into the reservoir space.

`The capillarity of the passages in the feed means is greater than that of the reservoir element and this relation is utilized to start and facilitate ow of ink from the reservoir element to the nib.

The design of the reservoir element is such that its capillarity is sufficient to hold ink at a height substantially equal to its own length but not the length of both itself andthe feed means. It will be noted that the length-of the feed means, from the front end of the reservoir element to the extreme front endy of the nib, is a substantial portion of the length of the reservoir element. Thus, if the capillarity of the reservoir element is such as to sustain a column of ink therein substantially equal to its own length, it follows that it would not hold a column equal to the length of the reservoir element and feed means combined. This would be true. whether or not the capillarity of the passages in the feed means is sufficient to lift the ink to the nib when the pen is in filling, point-end-up position, because regardless of the capillarity of those passages, the capillarity of the reservoir element is insufficient to hold a column of that length. It is within the scope of the invention to provide for so filling the passages in the feed means, particularly after initial filling. If the pen should have an open reservoir and be turned to pont-end-down position after filling, the ink would run out the front end until the column of ink reached a length, measured from thev front end of the nib, which could be sustained by the reservoir element and/or feed means according to the capillary strength of each.

Hence, although the pen is filled by capillary action, the ink feeds out freely and not according to capillary holding power, so that a condition is established in which the feed-out can be controlled by vacuum-reservoir condition, and it is so controlled. The valve assembly 60 in the rear barrel section ultimately closes the reservoir, but until the rear barrel section is applied to the pen, other means vmust be provided-for temporarily accomplishing that purpose, and this is done by the filler valve 19. The capillarity of the valve 19 is greater than that of the reservoir element, and great enough that it will easily hold the ink therein when the pen is re-inverted. However, the flow resistance is not so great as to prevent efficient fiow of ink therethrough when the rear end of the pen is inserted in the body of ink. Figs. 2l to 23 rep- (See below for reference to the filling action where the space 91 does not exist.) The pen is inserted in the ink to such depth that the level of the ink is above the lower end of the reservoir element. The hydrostatic head of the body of ink then forces ink through the capillary filler valve 19. This valve includes cells or passages, which, although communicating with one another, may be considered as discrete from the -standpoint of flow of ink therethrough by capillary action. The spaces or cells of the valve are represented at 200, but for the sake of simplicityin explaining the action, passages such as 202?. are

included in the representation. The action is the same in bothr cases. As the ink enters the passages (eg. 202), meniscuses 204 are formed, and as in known by those skilled in the art, such meniscuses serve to draw ink upwardly in those'spaces, adding to the effect produced by the hydrostatic head of the body of the ink. After the level of the ink inthe spaces reaches the upper end of the element 19 as shown in Fig. 22, the meniscuses no longer aid in lifting the ink since they are convex and extendupward beyond the walls forming the spaces. The convex meniscuses 206 are individual to the capillary spaces, but as the ink rises they join and lift from the walls of the spaces and unite'as indicated at 298. Finally all of the meniscuses form a fluid united body as indicated at 210and all forces provided by the meniscuses are dissipated and a fluid head is formed in the space 91 and liftednby the hydrostatic head ofthe main body of ratsam# i-ink until"u it reaches;` the `reseryoirj-elerrlentl y16. fhe ink @their flows' by capillary action `into'the reservoir-element an'dvlls'itto its capacity; A Y

When the pen is removed-from vthe body of ink and vre-inyert'ed` to point-end-down position, the cpillarity fof :the iille valve4 is sutiicient to f sustain fthe column of fink inthe reservoir.- 'HWhen-the column of ink in the reser- Vyo'ir' element below the valve drops and arareed space fforins betweenythat column and-the filler valve,-the ink is fretained in the ller valve against the pressure vexerted e'reon by theatmosphere. The drop or fall of the co1- umn'of ink would take place initially because of -the feed oftink lfrornjthe reservoir element intoftheA feed means, orlif'the feed means is full, `because of the Ifeed of ink "-fromithe nib onto the writing surface. Whether theY filler valve and reservoir element are spatially vseparated yor not, aspace or void` will form between the ink in those ffwo segments, the Separation ofthe, elements notA being sessentialltoxthe parting of theV portions ofthe ink. The ifllervalve'th'us acts Vas av plug-Mito'close and seal the rear dof kthe reservoir space.

Fig-23. indicates the rnanner'ofilling 4in the vabsence of a'spa'ce (such lasI 91) between the filler valve and reser-` Vvoirfelement The ink enters thefiller valve, meniscuses V211 form in the valve, in the manner described inv con- "nefction with Figs. `f21 and 22,'andwithout interruption Aforrn meniscuses1213in the reservoir element, andriillthe latter by Lcapillary action.V

"Fig."-24 represents the action takinglplace when ythe i fflle'r'vfatlve 19,produces a holding action on the ink in 'the reservoir element. This-figure represents the penle-in'vertedgto point-end-down position so that Vthe valveY s uppermostY and the reservoir element lowermost. Meniscuses 212;. are 'formed at the upper end ofthe capillary f spacesZGZ, which exert an upward-force onthe ink and Ihold the column of ink against the-force of gravity tending to lower it. The united -uid portion-216 isheld againstrdropping'by the meniscuses V212.

Uponsealing-the reservoir spacefa vacuum condition Htherein is produced in respon'seto'ffeed of the ink there- `from.V The feed of ink'from the reservoirA to the nib is con- :trolled bythatvacuurn condition together with the control ',fthroughthe capillary passages andrparticularlythe weir the reservoirlfelement feeds kthrough vthe fe'edmeans to 'the nibf The Tfeed means includes lthe feed bar 20 and 1` fthe collector 24, aswell `as a spacebetween thefeedbar 'gandfnib. The-primary feed is through the feed passages` V9;8, in the'feedbar, but ink in those passages'may also` feed bycapillary action into the arcuatepassage's 160 and `f'lslit''124as in the case offounrtafin pens heretofore-known. The YWriting tip 114 of the nib may 4curve downwardly on vits"pride"r'surf'ace to facilitate nengz'lgernent 'thereof lwith thehfyd Bar I.

'ffIn'k also` ov vs into-the control passage- V100 land 'feeds downthis'passageand into the weirl 108 conveniently but not-necessarily, theweir being-located below the reservoir element andk above the overflow cells' 116. Thecontrol Hpassage'160A is -of` suchdimensions throughout -all .of its "segrnents that when air must-pass into the-reservoir element kto replace inkfwithdrawn therefrom, it flowsv through suh control passage normally totheexclusion ofother -'passa-ges which include the'primaryfeed passages`=98 vand When the fpen'assumes fits Apoint-enti#down position pursuant tofllling,-such as a writing positiornthe inkfn vthe-passages 1168. *frfhefweiris the smallest portionfofthis {controlpassagefthat is'tofsay, it is the; smallest portion in `a"linearsuccession oflar-ge portions, and it exerts-the greatestholdingpower fortheink and determines the coni-ditio underfswhich' airVV willA passl therethrough into the reservoir, -Forexample, assunte as a starting point a con- Jdition'ofbalancediforces and a state of equilibrium in the `pen(V` The primary-feed passages 9Share lled and ink standstn-thecontrol passage l100 down-to and including tthe'weir. VThe vacuum condition -in the space above the inkL is of sufficient force (and usually greater)` to holdv the '.inl insuchstate of equilibrium, but notgreat-enou'gh to pull-inkom of the Weir. As writing begins,A ink is drawn out/of thenib onto the paper, and replenished in the nib from the passages98. Ink, in passing down thegpassages 98 to the nib, depletesthe quantity of inlt'in the reser- -voirland amore rareed or `higher-vacuum condition ex- .-ists. '.'vThesvacuum-condition then increases until air breaks fthroughgaandfasnoted above, `the air-passes through the 20=.weirfand Athe control passage 100. TheY air'in so passing through the -weirdoes-so in the'form of small bubbles .,vwhichpassupwardly through the -weir'and into the segmentilltlofY the `passage -and theninto the space rear- `warclly of thevcolumntof ink in the reservoir element.

Thespr-essure ofthe body of ink in -the reservoir elementis manifested in the Weir and such pressure-in the V.weir.,-is.theacondition that directly controlsV the passage rot fairtintol'the reservoir. vThe weir, although relied on stogrnodulate the degree of-vacuum by means of the pressureexerted bythe ink, can be cognizant of the pressure ...of the inkcolumnonly at fthe-height of the Weir. This pressure Visthe result of a relationship in the present case which includes anadditional factor as ,comparedV `awithaa conventionalvacuum-reservoir pen. In order-to avoidipossibleconict in the use of conventional terms .such ,as positive fand negative with respect to pressure, the;pres,suresreferred to herein will be designated downwardand upward. accordingas they exert inuence on thezink in the pen. In a vacuum-reservoir pen, the pres- -'.sure,ofthe,ink, as at the Weir, is the sum of the upward -.pressure in the reservoir space above the ink, and the Vdownward pressure exerted by the head of `ink in the --reservoir l,aboveithe control element ('weir). As Vreferred to;herein, thesu'm of the pressures involved is the algebraio sum, i.e., .upward and downward pressures added v algebraically. In the pen ofthe present invention the pressure `atthe weir is the result of the two pressures mentionedv above andxthe capillary strength of the-reservoir element. 4The latter is` an upward pressure. Such capil- -lary strength` is exerted. at all times by the reservoir elernentand-xassists'the ,vacuuml condition in retaining the f tnkrtherem. Whenair breaks through into the reservoir espace-1t.partiallyrellevesthe vacuurnin the'manner described above, and facilitates further feed ofthe-ink'to the .,55:

nib. The vacuum condition normally exceeds that required to :support the colurnnrof ink-at any given height,

, and entry ofadditional air decreases the vacuum pressure ndfacts to enable the ink to Vflow or pass more'freely to ihejllib.

The control of-the feed of ink to-the vnib also involves the-factor of capillarity of the reservoir element., The

`:,capillznit'y aids in maintaining the head of ink. In a per- Affectacaplllary (reservoir) element the ink storage spaces ,would iall be of exactly the same size and the head in 4all.l partsvof the element would be at exactly the same height As a practical matter, and as is vwell known, absolute accuracy is diicult of attainment in manufac- ...turingmethods and in the case of the reservoir/element herein used, it is quite difficult because the wall elements are -formedfY bysheet material of a thickness in the region of/.,G'Ol.l `VSuch sheet material obviously can only with Lthefgnost extremeV difculty be made absolutely accurate. :Thus ,such inaccuracies cause the head at different points to stand at different heights. The feed bar with its conktrolspassage -is extended :throughout the length of the reservoir element and the column of ink in that pasv sage is utilizedv for providing the head for sensing the column of ink in the reservoir element. The kink in this passageforms a continuous columnand it is the only body of ink to which Vthe weir is sensible. The column is the result of the pressures exerted by the different portions of the column in the reservoir and is' repre- `s'entative of those pressures.l Filling of the control passage 100 is assured by filling directly from the reservoir element in radial direction, or from the funnel space 178 in the event it does not readily fill directly from the reservoir element. The column of'ink in the control passage responds in height quite readily to the conditions in the reservoir element so that the desired pressures and consequent flow-control of ink are attained.

The control passage 100 can be easily formed to accu"ate dimensions by ordinary manufacturing methods. The feed bar is made of material such as plastic, having sufficient rigidity as noted above, so that by ordinary and well known methods a slot or groovecan be formed of determinate dimensions and within extremely close limits. This therefore eliminates the necessity for accurate dimensions of the spaces of the reservoir element.

Ideally, the control passage 100 should be of the same wall-to-wall dimension as the ink storage spaces of the in the direction out of the pen.

16 in excess of that required for writing purposes when an overflow condition develops. Such a condition would develop, for example, when the air in the reservoir space is expanded. When that air is expanded, the ink is forced This expansion may be caused by increase in temperature as in holding the pen in the hand, or by a drop in atmospheric pressure, such, for example, as when carrying the pen to elevated altitudes in an airplane. The ink, on expansion of the air, flows through the passage 168 in the collector and into the cells 166. This passage is of substantial capacity because of its relatively large radial dimension. The cells are of greater wall-to-wal] dimension than the passage and hence of lesser capillarity, and the total capacity of the cells is quite great whereby to contain and convey a substantial quantity of ink. The ink, in entering into the passage 168, first fiows along vthe full length of the passage and between the meeting faces of the end portions of the tins before entering into any of the cells because of the greater capillarity of the passage relative to the cells. 168 being filled, continued expansion of the air and consequent movement of the ink causes the ink to flow into the cells, as brought out in the Baker patent referred reservoir element, and hence equal to the mean capillarity thereof. This condition is closely approximated, but because of other considerations, modification therefrom is advisable. In the present instance, the wall-to-wall spacing of the reservoir element is in the neighborhood of .008 while that of the control passage is .009. Because of this slight difference, the level of the column of ink in the control passage will be slightly less than in the reservoir. However, the conditions are such that this relation may be taken into account and the control exercised by the Weir is determinedaccording to the column of ink in the control passage for controlling the condition in the reservoir space. The spacing of the reservoir element is selected as that capable of providing the necessary capillary filling and holding characteristics and at V4the same time permitting theiink to feed out in writing.

The dimension of thecontrolpassage (.009) is that dimension as nearly as possible equal to the reservoir spacing, but appreciably greater than the dimension of the weii (.007). The relation between the control passage and weir has two distinct advantages, one in Y manufacturing techniques and another in functioning of the pen. Manufacturing techniques make it desirable lthat no less than a .002 difference exist in order to eliminate objectionably close tolerances. With respect to the functioning of the pen, air bubbles abruptly increase in speed in passing from the weir into the control passage, and continue at a. relatively great speed in flowing up the passage. The air bubbles are quite small relative to't'he passage (i.e., segment 106 thereof) and in passing through the ink, the ink is enabled to flow around the bubbles,

to above.

A reverse and corresponding action takes place in emptying the cells in a writing-out operation. In writing, the capillarity between the nib and Writing surface draws ink out of therpen. The ink to replenish ink drawn from the nib proceeds from the overflow cells in preference to the reservoir element, as also explained in the Baker patent mentioned. The flow of ink is from the cells into v the passage 168, and then through spaces 160 and 162 to the nib in the manner explained above.

l graded in size uniformly, but because of preferred manuv facturingtechniques, they are formed in groups, with those in each group all of the same size and those of successive groups progressing in size as mentioned. This gradationrof cell size provides the necessary capillary to air lockV in this action.

and it is not necessary for the bubbles' to push the colf umn of ink ahead of them in passing up the passage. Thus air lock from this source is eliminated. Continuity of ow of ink through the passage is improved. `In this connection reference is also made to the pilot passage 112 in the control passage, as the air bubbles pass upwardly in the outer large portion a continuous column is maintained in the pilot passage to the Weir. Hence, the construction and relation operate to minimize variation in line intensity in the breathing cycles. The dimension of the weir (.007) is selected as the proper dimension Vto maintain the column of ink according to the various pressures described above.

Normally ink does not flow downwardly from and out of the weir but if it should, in unusual circumstances, it would flow in to the portion of the passage, and into the feed passages 98 and thus to the nib,v as set out above.

holding power in each cell according to its height above the nib.

The positioning of the capillary passage 168 and air flow passage 170 on opposite sides of the collector works to a beneficial effect. The ink inentering the cellsk 166 does so from the passage 168 and migrates upwardly and drives the air out ahead of it, eliminating any possibility For further details of the action with respect to the collector, reference may be made to the Baker patent mentioned above.

The ink in flowing into the passage 168 may do so directly from the end thereof from the open end ink storage spaces in the reservoir element. Ink may also ilow into the other radial `slots 176 and then into the funnel space 178 and from there into the passage 168. Another important advantage of the invention is the provision for drain-back of the collector. If the collector should till or partially fill, and later the pen be turned to point-end-up position, the collector is emptied substantially immediately. The ink in the reservoir element forms a continuous column as will be understood because of the capillary nature of the reservoir element. This ink column is continued uninterruptedly to the passage 168 and overflow cells. Thus when the pen is inverted Y to point-end-up position, the ink in the passage 168 and feed passages, namely, the two main passages 98. As a onsequence, ,a ,ready ink supply may not be available However, upon the passageV asseoir at the nib for instant writing were it not for provision to avoid that circumstance; in the present construction, such condition is avoided by the pilot channels 104 at the bottom of the ink feed passages. These channels are of very small dimension, as indicated above (.002"), and remain substantially full (after initial filling) even though the pen remains for a long period of time in point-end-up position. Thus when the pen is again re-inverted to point-end-down position after the collector and main large portions of the feed passages have been drained, the pilot channels quickly supply ink to the nib. The pen is accordingly always ready for instant writing.

Drain-back ofthe collector obviates an objection to previous pens from the standpoint of leakage due to expansion. Comparison is made with collector arrangements previously known in which the ink once forced into the collector remained there in normal functioning of the pen until drawn out through the nib in writing. In that case, if a second expansion condition occurred while the collector was full, the pen would likely leak, but in the present case the collector would be emptied by drain-back (if not by writing) before a second expansion condition occurred.

There may be feed of ink to a limited extent from the reservoir element through the passage 16S and spaces 160 and 162. However, this condition is incidental to the normal function of the pen and the communication between the passage 168 and space 160 is primarily for the purpose of writing out the ink from the, overliow cells.

The capability of the pilot channels '104 to hold ink when the pen is in point-end-up position prevents nib dry-out which might otherwise occur because of drainback, were it not for the pilot channels. Ink forms a film in the narrow arcuate capillary space 162 in register with the nib slit 124, which maintains the nib in moist condition. Ink also finds its way into the space 128 between the nib and surface 48. Hence a lm of ink is maintained on each side of the nib. The desired relationship between the elements for maintaining the capillary-dimension spaces is accomplished by the solid mounting of the collector, feed bar and nib. The collector has firm support at each end in the front barrel section; the feed bar is of great length and has firm bearing support in a substantial portion of the bore of the collector; and the nib has firm support at its rear end in the collector and at the shelf 129.

The foregoing pen provides for substantially uniform line intensity throughout its full range from full to empty condition; leakage is substantially eliminated from the sources mentioned, and also any leakage that may otherwise result from jarring the pen, because of the tortuous path of the various passages between the reservoir element and the exterior; any disadvantages from loss of capillary holding power are obviated since the feed-out of ink is under control of vacuum condition of the reservoir.

If it is desired, eg., for manufacturing reasons, not to maintain the precision in the dimensions of the parts to attain the accuracy of spacing mentioned, the transfer of ink to the nib may be aided by a capillary pad on or associated with the nib. Such a construction is shown in Fig. 25 Where pad elements 218 and 220 are utilized, the former between the feed bar and nib, andthe latter between the nib and the surface 48. Thesel two pad elements may be separate pieces, or in the form of a sleeve fitted over the nib. These pad elements fill the spaces in wall-to-wall direction and maintain constant contact between the nib and the related elements. Thus any inaccuracies, that may occur in any of the three elements between which they are placed, are overcome. It will be understood that the pad elements are in overlying relation to or in register with the nib slit. It is not necessary that a pad element be provided in each of the spaces mentioned since it may be desirable to have such a pad in Qnly one of the spaces, either below or above. Having a pad below in the space 162 :is more desirable, but it may also be desired to have a pad above the nib so as to produce a compressing action thereon when the nib sections are flexed in writing. This action facilitates transfer of ink from the pad to the nib slit, the pad obtaining its ink from the lower pad through the nib slit and possibly from the film of ink already in the upper space 128. The pad or pad elements may be made from such materials as cotton Hock, plastic synthetic cobwebs, thinly sliced sponge rubber, natural cotton fibres, synthetic plastic sponge-like structures, cloth, etc. It is also alternatively proposed that such pad or pad elements be formed by spraying material such as plasticrcobwebbing on the nib at the desired location, the material bonding to the nib. Such pad or pad elements may be used to great advantage between other elements of a pen where it is desired to assure effective capillary transfer of ink between those elements. This may be in association with a nib, or it may be between other elements.

We claim:

1. A combination vacuum-capillary reservoir fountain pen comprising: a writing point; a capillary reservoir element for holding ink therein by capillary action; feed means having capillary passages connecting said reservoir element with said point and with atmosphere, said capillary passages holding ink therein by capillary action; and means closing ofi said reservoir element Afrom direct air venting connection with atmosphere so that said reservoir elements only connection with atmosphere is through ink in said capillary passages; whereby a partial vacuum is created in said reservoir element in response to flow of ink therefrom, said partial vacuum acting to hold ink in said reservoir element, said partial vacuum being increased by flow of ink from the reservoir element and decreased solely by air bubbling through ink in one of said passages and into said reservoir element; the ink fiow of the fountain pen thus being jointly controlled by the capillarity of said capillary reservoir element and the partial vacuum.

' 2. The invention defined in claim l further provided with means for exposing the closed off reservoir element rdirectly to atmosphere through a path other than said capillary passages to enable filling of said capillary reservoir element solely by capillary action upon insertion of it into a body of ink and for closing said element after filling to enable writing under combined vacuum and capillary control.

3. The invention defined in claim l further characterized in that the capillary reservoir element has a capillary strength sufiicient to sustain a column of ink of substantially its own length but insufficient to sustain a column of ink of the combined length of itself and said feed means.

4. The invention defined in claim 1 wherein said capillary reservoir element has a filling entrance at the rear thereof and wherein there is provided a porous member covering said filling entrance, said porous member having a porosity permitting the passage of ink therethrough during filling and retaining ink therein after filling for prohibiting the passage of air therethrough after filling thereby effectively sealing said filling entrance to enable Writing under combined vacuum and capillary control.

5. The invention defined in claim l wherein said reservoir element has a filling entrance at the rear thereof and where there is provided a removable and replaceable member for exposing the filling entrance to permit filling of the reservoir element and for closing the filling entrance after filling to seal said filling entrance to permit writing under combined vacuum and capillary control.

6. The invention defined in claim 1 wherein said capillary reservoir element has a filling entrance at the rear thereof, and wherein there is provided a porous member covering said filling entrance and a removable and replaceable closure member for covering and uncovering said porous member to thereby expose said porous mem@ 19 ber for lling said reservoir element therethrough and to thereafter close oisaid porous member and said entrance rand said reservoir element for writing under combined vacuum and Vcapillary control.

7. 'The invention defined in claim 1 wherein said feed means includes an overow ink collector having capillary overow cells communicating with said capillary passages.

References Cited in the le of this patent UNITED STATES PATENTS 20 Y Y Hardesty Aug. 13, 1935 Sypher Aug. 10, 1937 Zodtner Sept. 19, 1950 Wittnebert May 29, 1951 Zodtner et al June 15, 1954 Rickmeyer July 5, 1955 Kovacs Oct. 16, 1956 Rigondaud Nov. 5, 1957 FOREIGN PATENTS Great Britain Dec. 4, 1947 Sweden Sept. 25, 1951 France Apr. 21, 1954 Great Britain May 5, 1954 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,935,044 May 3. 1960 Frederick R. Wttnebert et al.v

It is herebY certified that error appears in the-printed specification of the above numbered patent requiring correction and 'that the said Letters Patent should read as corrected below.

Column 7, line 60, for "capillary" read capllarty column 12, line 61, for "as in" read as s line 68, for "upward" read upwardly same line 68, for'flglhe" read These column 13, line 31, for "pen" read pen line 51, for "the", first occurrence, read The same column 13, line 70, for "116" read 166 lco'lulnnn 14, line l, for npassages read passage .linev 70, for .ormedf" read formed column 17, line 48, for "full", second occurrence, read fully Signed and sealed this 25th day of October 1960.

(SEAL) Attest:

KARL H. AXLTNE ROBERT C. WATSON Attesting Ofcer Commissioner of Patents 

